This invention relates generally to cathode cartridges for electroplating testers, and more particularly to a cathode cartridge for an electroplating tester, with which silicon wafers, glass substrates, ceramic substrates, or the like coated with a metal layer can be plated precisely.
In recent years, the plating technique has extensively been used in various fields of technology, such as one which lends itself to wiring for semiconductor chips. In the field of semiconductor-related industries, fine-pitch wiring within and on the semiconductor chips is required for realizing high-density packaging and high performance of an electronic circuit. Among wiring methods that prevail recently, the so-called Damascene process is widely adopted. The Damascene process is a method in which a conductive material is embedded through a plating process into a channeled pattern of wiring formed through a dry etching process after forming an interlayer insulating film.
One of the latest applications of the plating technique, called LIGA (abbreviation of the German phrase, Lithographie Galvanoformung Abformung), is directed to manufacture of parts of micromachines. The LIGA forms a mold of an acrylic resin using X-rays, and thick metal plating is deposited in the mold, so that very small metal parts are molded.
To implement the plating techniques as exemplified above, the metal plating should be uniformly deposited on the channeled pattern formed in an object to be plated. In this respect, the applicant for the instant application has proposed in Japanese Patent Application No. 2000-152342 (published under JP 2001-335996 A; corresponding to U.S. Ser. 2002/0008026 A1, and EP 1164209 A2) an electroplating tester and a cathode cartridge for use with the electroplating tester, with which a uniform layer of plating can be formed on a surface to be plated of an object to be plated.
According to the disclosure, a cathode cartridge 70 for use with electroplating testers, as shown in FIG. 12, includes a tabular cathode conductor 71, a front insulator 72, a rear insulator 73, and an elastic thin board 74. The tabular cathode conductor 71 includes an opening having the same shape as a surface Wa to be plated of an object W to be plated as a negative, a plurality of protrusions 71a in contact with a rim of the surface Wa to be plated, and an exposed portion which is not to be immersed in plating solution and thus connectible with a direct-current power supply. The front insulator 72 includes an opening having the same shape as the surface Wa to be plated, and covers the front side of the cathode conductor 71. The rear insulator 73 is a tabular body including a groove 73a into which the object W to be plated is fitted, and a groove 73b into which the cathode conductor 71 is fitted. The elastic thin board 74 is to be sandwiched between the object W to be plated and the rear insulator 73.
However, the conventional technique as disclosed in JP 2001-335996 A would disadvantageously allow plating solution L to reach a portion 71b, etc. other than the rim Wb of the surface Wa to be plated of the object W to be plated, a side surface Wc of the object W to be plated, and the protrusions 71a of the cathode conductor 71, as shown in FIG. 13. Accordingly, one of the problems associated with the conventional cathode cartridge for use with electroplating testers is that negative portions other than the surface Wa to be plated of the object W to be plated could be immersed in the plating solution.
The state of the art is at the point where wiring on or within semiconductor chips is constituted of a fine wire measuring 0.5 xcexcm or smaller in diameter, and thus requires a very high degree of plating precision. However, if negative portions other than the surface Wa to be plated of the object W to be plated were immersed in the plating solution, an error could occur in areas of the surface to be plated, with the result that required plating precision would not be obtained. Consequently, in order to achieve a high degree of plating precision, the negative portions other than the surface Wa to be plated of the object W to be plated need be insulated from the plating solution.
The present invention is made to eliminate the above-described disadvantages.
It is an exemplified general object of the present invention to provide a cathode cartridge for an electroplating tester capable of insulating negative portions other than a surface to be plated of an object to be plated.
A cathode cartridge for an electroplating tester according to the present invention comprises: a tabular cathode conductor that includes an opening having the same contour as a surface to be plated of an object to be plated as a negative, a plurality of protrusions in contact with a rim of the surface to be plated, and a power-supply connection portion connectible with a power supply at a portion thereof which is not to be immersed in plating solution; a tabular first insulator that covers one surface to be plated of the object to be plated and includes an opening having the same contour as the surface to be plated, a first sealant fit-in groove which is formed along a circumferential edge of the opening and into which a first sealant is fitted, a cathode conductor fit-in groove which is formed at an outside of the first sealant fit-in groove and into which the cathode conductor is fitted, and a power-supply connection portion slot which is formed contiguously with the cathode conductor fit-in groove and into which the power-supply connection portion is fitted; and a tabular second insulator that covers the other surface reverse to the surface to be plated of the object to be plated and includes an object-to-be-plated fit-in groove into which the object to be plated is fitted, a second sealant fit-in groove which is located at an outside of the object-to-be-plated fit-in groove so as to come in a position outside an inlet of the power-supply connection portion slot when the second insulator is combined with the first insulator and into which the second sealant is fitted. The first insulator and the second insulator are combined together so that the first insulator and the second insulator sandwich the object to be plated and the cathode conductor.
The above construction allows the first sealant to be brought into contact with the rim of the surface to be plated of the object to be plated, and the second sealant to be brought into contact with the surface of the first insulator at an outside of a position where the object to be plated is located, when the first insulator and the second insulator are combined together, thus serving to insulate the rim and side of the surface to be plated of the object to be plated from the plating solution. Moreover, an inlet of the power-supply connection portion slot is properly positioned between the first sealant and the second sealant when the first insulator and the second insulator are combined together; thus, portions other than the protrusions of the cathode conductor can be insulated from the plating solution.
The first insulator may further include a second insulator fit-in groove which is formed at an outside of the cathode conductor fit-in groove and into which the second insulator is fitted when the first insulator and the second insulator are combined together, so that the opening of the first insulator and the surface to be plated of the object to be plated fitted in the object-to-be-plated fit-in groove of the second insulator may be appropriately aligned with ease. To be more specific, the opening of the first insulator and the surface to be plated of the object to be plated fitted in the object-to-be-plated fit-in groove of the second insulator can be positioned directly opposite to each other, when the first insulator and the second insulator are combined together.
The first insulator and the second insulator may be combined together with ease by fastening up with screws made of plastic. The first insulator and the second insulator may be combined using any means other than the screws, such as a clip.
Further, a laminar elastic body covering the surface reverse to the surface to be plated of the object to be plated may be fitted into the object-to-be-plated fit-in groove of the second insulator. When the first insulator and the second insulator are combined together, the object to be plated fitted in the object-to-be-plated fit-in groove are pushed toward the first sealant fitted in the first sealant fit-in groove of the first insulator. As a result, the rim of the surface to be plated of the object to be plated can be kept in intimate contact with the first sealant. Thus-achieved intimate contact of the rim of the surface to be plated of the object to be plated with the first sealant can contribute to more secure insulation of the rim and side of the surface to be plated of the object to be plated from plating solution.
The laminar elastic body also serves to fill up a gap between the object to be plated and the object-to-be-plated fit-in groove. To be more specific, the elastic body having the same thickness as the gap between the object to be plated and the object-to-be-plated fit-in groove may be fitted into the object-to-be-plated fit-in groove of the second insulator; thereby the gap between the object to be plated and the object-to-be-plated fit-in groove can be closed up. No-gap contact between the object to be plated and the object-to-be-plated fit-in groove as thus achieved allows the object to be plated fitted in the object-to-be-plated fit-in groove to be securely pushed toward the first sealant fit-in groove fitted in the first sealant fit-in groove.